The format is supported by the free Traktor 2.9 update, which launched today. The files themselves are available now from six retailers: Beatport, Bleep, Juno, Traxsource, whatpeopleplay and Wasabeat. Labels selling Stems include 50Weapons, R&S, Ghostly International and Hypercolour.

Each Stem file breaks a track down into four parts, generally rhythm, lead, bass and vocals. The format has been designed for use with NI’s Traktor devices and software, though Stems is open source, opening it up for potential use on other platforms.

There’s more information and some free stems at the Native Instruments website. You can watch a demonstration of the format in the video below.